1. Technical Field
The present invention relates to mechanical assemblies of metals, and in particular to mechanical assemblies of metal parts having incompatible ionization energies. Mechanical assemblies according to the present invention may be employed in a variety of mechanisms such as fishing reels and bicycle components.
2. Description of Background
Material set forth in U.S. Pat. No. 6,209,816 B1 not included in the present disclosure is herein incorporated by reference thereto. The present disclosure is a rewriting of certain aspects of the disclosure in Pat. No. 6,209,816 B1.
The present invention is directed to building certain machines that require contact of parts made from metals having incompatible ionization energies. If the ionization energies of metals in contact are sufficiently dissimilar, electrolytic corrosion may occur when current flows between them in the presence of an electrolyte such as, for example, saltwater.
Human-powered rotary machines optimally are lightweight for ease of operation and at the same time rigid to withstand over time the irregular stress and strain that human rather than mechanical application of power to the machines entails. Steel, for example, while rigid in having a high modulus of elasticity, is often undesirably heavy for such applications. In addition to lightness of weight and rigidity, reducing bulk is also desirable in manufacturing human-powered rotary machines, so that they are not unwieldy. Manufacturing parts for such machines of synthetic polymers, for example, may require unacceptable bulk in order to achieve sufficient rigidity. In some applications, furthermore, synthetic-polymer manufactured parts lack the desired texture and cannot lend sought-after quality to the appearance.
Aluminum alloys provide desirable texture and high-grade appearance, and have moduli of elasticity higher than synthetic polymers, but lower than steel. Likewise is the case with zinc alloys, titanium and titanium alloys.
Magnesium alloys are lightweight and highly rigid, but of course lack the strength of steel. Employing magnesium alloys in combination with iron or steel in manufacturing machine components can serve to reduce weight while maintaining operatively sufficient strength and rigidity. Iron and steel have ionization energies incompatible with magnesium alloys, to the extent that electrolytic corrosion may occur between them if they are in direct contact and come into the presence of an electrolyte such as saltwater or even air.
An object of the present invention is to prevent electrolytic corrosion in machine parts manufactured of magnesium alloy and employed in combination with machine parts made of materials having ionization energy incompatible with magnesium alloy.
The present invention in one aspect is a mechanical assembly of a magnesium alloy first part and a second part of another metal coupled to the magnesium alloy part at a clearance therewith, and a filling agent injected into the clearance between the first and second parts.
The second part may be an aluminum or zinc alloy; alternatively, the second part may be titanium or titanium alloys, or stainless steel.
The magnesium alloy first part may be anodized.
Wherein the second part is made of aluminum or zinc alloy, it may be coupled to and in direct contact with a steel part in a mechanical assembly according to the present invention.
The filling agent may be a liquid for injection into the clearances by capillary action. In addition, the filling agent may be a liquified adhesive that solidifies after insertion.
The filling agent improves anti-corrosion properties of the mechanical assembly by acting as an insulator against electrolytic corrosion.
In another aspect, the present invention is a mechanical assembly that includes: a magnesium alloy first part; a lower ionization-energy stainless steel or titanium/titanium alloy second part coupled to the magnesium alloy first part; an insulating material interposed between and in direct contact with the first and second parts; and a filling agent injected into clearances between the first part and the second part or the insulating material.
The insulating material electrically insulates the magnesium alloy from the lower ionization-energy stainless steel or titanium/titanium alloy to make electrolytic corrosion unlikely.